Users are increasingly performing tasks using remote computing resources, often referred to as part of “the cloud.” This has many advantages, as the resources will typically be purchased, managed, and configured by a resource provider. In situations such as a virtual private network (VPN), users can take advantage of these resources as if the users were directly connected to the network. In order to provide such access from across a public network, however, robust authentication mechanisms are typically used to ensure that only authorized users are permitted to access the resources via VPN. These robust mechanisms can be very resource intensive and can take a significant amount of time to process incoming requests. This exposes a potential vulnerability, as an attacker may be able to overwhelm the authentication mechanism and prevent legitimate users of the network from being authenticated to gain or maintain access.